In her chemistry class, Nadia took 5 quizzes. Her scores were 78, 75, 80, 83, and 84. What was her average score on the quizzes?
Solution: The average is the sum of her scores divided by the number of scores. There are 5 scores and their sum is $78 + 75 + 80 + 83 + 84 = 400$ Her average score is $400 \div 5 = 80$.